The contributions of the innate and adaptive immune response in the control of human tumor growth are well-characterized (Vesely M D et al., (2011) Annu Rev Immunol 29: 235-271). As a result, antibody-based strategies have emerged that aim to enhance T cell responses for the purpose of cancer therapy, such as targeting T cell expressed stimulatory receptors with agonist antibodies, or inhibitory receptors with functional antagonists (Mellman I et al., (2011) Nature 480: 480-489). Antibody-mediated agonist and antagonist approaches have shown preclinical, and more recently clinical, activity. An important stimulatory receptor that modulates T cell, Natural Killer T (NKT) cell, and NK cell function is the OX40 receptor (also known as OX40, CD134, TNFRSF4, TXGP1L, ACT35, and ACT-4) (Sugamura K et al., (2004) Nat Rev Immunol 4: 420-431). OX40 is a member of the tumor necrosis factor receptor superfamily (TNFRSF) and signaling via OX40 can modulate important immune functions.
OX40 can be upregulated by antigen-specific T cells following T cell receptor (TCR) stimulation by professional antigen presenting cells (APCs) displaying MHC class I or II molecules loaded with a cognate peptide (Sugamura K et al., (2004) Nat Rev Immunol 4: 420-431). Upon maturation APCs such as dendritic cells (DCs) upregulate stimulatory B7 family members (e.g., CD80 and CD86), as well as accessory co-stimulatory molecules including OX40 ligand (OX40L), which help to sculpt the kinetics and magnitude of the T cell immune response, as well as effective memory cell differentiation. Notably, other cell types can also express constitutive and/or inducible levels of OX40L such as B cells, vascular endothelial cells, mast cells, and in some instances activated T cells (Soroosh P et al., (2006) J Immunol 176: 5975-5987). OX40:OX40L co-engagement is believed to drive the higher order clustering of receptor trimers and subsequent signal transduction (Compaan D M et al., (2006) Structure 14: 1321-1330).
OX40 expression by T cells within the tumor microenvironment has been observed in murine and human tumor tissues (Bulliard Y et al., (2014) Immunol Cell Biol 92: 475-480 and Piconese S et al., (2014) Hepatology 60: 1494-1507). OX40 is highly expressed by intratumoral populations of regulatory T cells (Tregs) relative to conventional T cell populations, a feature attributed to their proliferative status (Waight J D et al., (2015) J Immunol 194: 878-882 and Bulliard Y et al., (2014) Immunol Cell Biol 92: 475-480). Early studies demonstrated that OX40 agonist antibodies were able to elicit tumor rejection in mouse models (Weinberg A D et al., (2000) J Immunol 164: 2160-2169 and Piconese S et al., (2008) J Exp Med 205: 825-839). A mouse antibody that agonizes human OX40 signaling has also been shown to enhance immune functions in cancer patients (Curti B D et al., (2013) Cancer Res 73: 7189-7198).
OX40 and OX40L interactions also have been associated with immune responses in inflammatory and autoimmune diseases and disorders, including mouse models of asthma/atopy, encephalomyelitis, rheumatoid arthritis, colitis/inflammatory bowel disease, graft-versus-host disease (e.g., transplant rejection), diabetes in non-obese diabetic mice, and atherosclerosis (Croft M et al., (2009) Immunol Rev 229(1): 173-191, and references cited therein). Reduced symptomatology associated with the diseases and disorders has been reported in OX40- and OX40L-deficient mice, in mice receiving anti-OX40 liposomes loaded with a cytostatic drug, and in mice in which OX40 and OX40L interactions were blocked with an anti-OX40L blocking antibody or a recombinant OX40 fused to the Fc portion of human immunoglobulin (Croft M et al.; Boot E P J et al., (2005) Arthritis Res Ther 7: R604-615; Weinberg A D et al., (1999) J Immunol 162: 1818-1826). Treatment with a blocking anti-OX40L antibody was also shown to inhibit Th2 inflammation in a rhesus monkey model of asthma (Croft M et al.; Seshasayee D et al., (2007) J Clin Invest 117: 3868-3878). Additionally, polymorphisms in OX40L have been associated with lupus (Croft M et al.).
Given the role of human OX40 in modulating immune responses, provided herein are antibodies that specifically bind to OX40 and the use of these antibodies to modulate OX40 activity.